Biotemas (Sep 2012)
Allelopathic interference of aqueous extracts of chinaberry on the germination and initial growth of tomato
Abstract
Allelopathy effects vegetative development and is caused by chemical substances produced and released by surrounding plants. The objective of this work was to investigate the allelopathic activity of aqueous extracts of fresh and dried leaves and fruits of chinaberry (Melia azedarach L. – Meliaceae) on the germination and initial growth of tomato. The extracts were prepared at concentrations of 1, 2 and 4% and analyzed for their pH and osmotic potential. The experiment consisted of four replications of 25 tomato seeds that were distributed in Petri dishes containing two sheets of germitest paper. Each plate received 2mL of an extract. The seeds were evaluated for percentage of germination (PG), germination rate (VG) and germination speed index (IVG). The initial growth was assessed based on the length of the radicle, hypocotyl and leaf, and fresh and dry weight. All concentrations of the extracts exhibited inhibitory activity on germination and radicle growth, and the inhibitory effect increased as the concentration of the extract increased. Extracts from dried leaves had the greatest effects. The osmotic potential and pH of the extracts did not vary significantly compared to the control, indicating that the allelopathic effect was due to the allelochemicals in the extracts.
